Crude oils that have one or more unsuitable properties that do not allow the crudes to be economically transported, or processed using conventional facilities, are commonly referred to as “disadvantaged crudes”. Disadvantaged crudes may have a high viscosity that renders the disadvantaged crude undesirable for conventional transportation and/or treatment facilities. Disadvantaged crudes having high viscosities, additionally, may also include hydrogen deficient hydrocarbons. When processing disadvantaged crudes having hydrogen deficient hydrocarbons, consistent quantities of hydrogen may need to be added to inhibit coke formation, particularly if elevated temperatures and high pressure are used to process the disadvantaged crude. Hydrogen, however, is costly to produce and/or costly to transport to treatment facilities.
Conventional methods of reducing the high viscosity of the disadvantaged crude include contacting the disadvantaged crude at elevated temperatures and pressure with hydrogen in the presence of a catalyst. Sediment formed during processing may accumulate in the larger pores of the catalyst while viscosity and/or other properties are reduced by contact of the feed with the active metals in the smaller pores of the catalyst that the sediment and/or large compounds contributing to viscosity can not enter. Disadvantages of conventional catalysts are that they require significant amounts of hydrogen in order to process the hydrogen deficient hydrocarbons and that the larger pores of the catalyst become filled. Thus, the activity of the catalyst is diminished and the life of the catalyst is reduced. To counteract the diminished activity and/or increase throughput per volume of feed, the catalyst may contain a significant amount of metal and/or combination of metals. As more metal is used in a catalyst, the pores of the catalyst become filled resulting in catalyst that have that are diminished pore size due to the metal occupying space in the pore. To accommodate more metal, catalysts with larger pore diameters may be made, however, an increase in pore diameter may reduce the surface area of the catalyst.
It would be desirable to have a process and/or catalyst for reducing the viscosity of a disadvantaged crude at selected temperatures and minimal pressures. Such a catalyst could be used at elevated temperatures and minimal pressures.
U.S. Pat. No. 4,225,421 to Hensley; U.S. Pat. No. 5,928,499 to Sherwood, Jr. et al U.S. Pat. No. 6,554,994 to Reynolds et al., U.S. Pat. No. 6,436,280 to Harle et al., U.S. Pat. No. 5,928,501 to Sudhakar et al., U.S. Pat. No. 4,937,222 to Angevine et al., U.S. Pat. No. 4,886,594 to Miller, U.S. Pat. No. 4,746,419 to Peck et al., U.S. Pat. No. 4,548,710 to Simpson, U.S. Pat. No. 4,525,472 to Morales et al., U.S. Pat. No. 4,499,203 to Toulhoat et al., U.S. Pat. No. 4,389,301 to Dahlberg et al., and U.S. Pat. No. 4,191,636 to Fukui et al. describe various processes, systems, and catalysts for processing crudes and/or disadvantaged crudes.
U.S. Published Patent Application Nos. 20050133414 through 20050133418 to Bhan et al.; 20050139518 through 20050139522 to Bhan et al., 20050145543 to Bhan et al., 20050150818 to Bhan et al., 20050155908 to Bhan et al., 20050167320 to Bhan et al., 20050167324 through 20050167332 to Bhan et al., 20050173301 through 20050173303 to Bhan et al., 20060060510 to Bhan; 20060231465 to Bhan; 20060231456 to Bhan; 20060234876 to Bhan; 20060231457 to Bhan and 20060234877 to Bhan; 20070000810 to Bhan et al.; 20070000808 to Bhan; 20070000811 to Bhan et al., and U.S. patent application Ser. Nos. 11/866,909; 11/866,916; 11/866,921 through 11/866,923; 11/866,926; 11/866,929 and 11/855,932 to Bhan et al., filed Oct. 3, 2007, are related patent applications and describe various processes, systems, and catalysts for processing crudes and/or disadvantaged crudes.
U.S. Pat. No. 4,225,421 to Hensley et al. describes a catalyst having a bimodal pore structure and improved effectiveness in the desulfurization and demetallation of metal-containing hydrocarbon streams. This catalyst has a surface area between 140 and 300 m2/g, 60-95% of its pore volume in pores having a pore diameter from 2-200 Å, 1-15% of its pore volume in pores having a pore diameter from 200-600 Å, and 3-30% of its pore volume in pores having a pore diameter from 600-10,000 Å as determined using nitrogen adsorption methods. Operating pressures range from 5.5 MPa to 20.7 MPa. Operating temperatures range from 371° C. to 454° C. In Tables I through III, the average pore diameter of the catalysts range from 137 Å to 162 Å.
U.S. Pat. No. 5,928,499 to Sherwood, Jr. et al. describes a process for hydrotreating a hydrocarbon feed containing components boiling above 1000° F. and sulfur, metals and carbon residue utilizing a heterogeneous catalyst having a specified pore size distribution, median pore diameter by surface area and pore mode by volume, to give a product containing a decreased content of components boiling above 1000° F., decreased sulfur, metals and carbon residue is disclosed. The catalyst includes an porous alumina support containing less than or equal to 2.5 wt % silica on a finished catalyst basis, and bearing 2.2 wt % to 6 wt % of a Group VIII metal oxide, 7 wt % to 24 wt % of a Group VIB metal oxide and preferably less than 0.2 wt % of a phosphorous oxide. The catalyst may be characterized as having a total surface area of 215 to 245 m2/g, a total pore volume of 0.82 to 0.98 cc/g, a median pore diameter by surface area of 91 to 104 Å, and a pore diameter distribution in which 22.0 to 33.0% of the total pore volume is present as macropores of a diameter greater than 250 Å, 67.0 to 78.0% of the total pore volume is present as micropores of a diameter less that 250 Å. The pore volumes were determined using mercury porosity measurements. Operating pressures range from 1800-2500 psig (approximately 12 MPa to 17 MPa. Operating temperatures range from 700° F. to 900° F. (371° C. to 384° C.).
U.S. Pat. No. 5,221,656 to Clark et al. describes a hydroprocessing catalyst that has a surface area of greater than 220 m2/g, a pore volume of about 0.23-0.30 cc/g in pores greater than about 600 radius Å, an average pore radius of about 30-70 Å in pores less than 600 Å, and an incremental pore volume curve with a maximum at about 25-50 Å radius. The hydrocarbon feed is contacted with the catalyst at an operating pressures range of about 13.8 MPa (2000 psig) and a temperature of 421° C. (790° F.).
As outlined above, there has been considerable effort to develop methods and systems to economically convert disadvantaged crudes to useable products. It would be advantageous to be able to convert crudes with a high viscosity, and therefore a low economic value, into a crude product having a decreased viscosity content by contacting the crudes with a catalyst with a minimal amount of sediment formation. It would also be advantageous to consume a minimal amount of hydrogen during processing. The resulting crude product may, thereafter, be converted to selected hydrocarbon products using conventional hydrotreating catalysts.